HKEY_LOCAL_MACHINE\Software\Microsoft\SMS\DP\RamDiskTFTPBlockSize
Type Reg_Dword
Value: 16384 Dec (Do not use higher value than this!)
((Recommend that you increase this setting in multiples (4096, 8192, 16384, and so on) and that you not set a value higher than 16384.))

Restart WDS Service
Remember the higher value the more risk of packet loss if bad network Connection.
You have to try this out carefully in your network environment.
If experiencing problems, try lower value.

You may be correct that this is a more technically correct approach, but it is also significantly more difficult and likely to be entirely unsupported.
What would be vastly better would be for Microsoft to add proper supported configuration options to improve this.